The present invention relates generally to air movement and filtration, and more particularly to structures and methods establishing a seal against air bypassing filtration elements.
Air filtration and movement systems as used in building structures provide a portion of an air recirculation system. Most modem building structures include some form of air movement, and often filtration, systems integrated into the building structure. In certain applications, for example hospitals and manufacturing cleanrooms, filtration plays a particularly important role in the air recirculation system. The present invention will be illustrated in the context of such applications requiring high levels of air quality or particular patterns of air flow within a controlled environment.
The ceiling structure supports filter panels and the controlled environment, typically the floor or side-walls, includes a number of air intake openings. Air forced through the filters moves into and through the controlled environment at a controlled rate and eventually enters the air intake openings. An air return system moves the air back above the ceiling and through the filters to establish a recirculation path for the air. In some applications, air flow is reversed moving upward through the controlled environment, through a set of filters at the ceiling, and thereafter returning to the controlled environment. In any case, particular levels of air purity and air flow control are required and depend on air flow passing only through the filters.
The following US patent documents, the disclosures of which are hereby fully incorporated by reference thereto, teach a variety of aspects of cleanroom ceiling structures including lighting, air movement, and fire suppression elements therein: U.S. Pat. No. 5,794,397 issued Aug. 18, 1998 and entitled Clean Room Ceiling Structure Light Fixture Wireway; U.S. Pat. No. 5,681,143 issued Oct. 28, 1997 and entitled Damper Control System for Centrifugal Fan; U.S. Pat. No. 5,613,759 issued Mar. 25, 1997 and entitled Light and Filter Support Structure; U.S. Pat. No. 5,207,614 issued May 4, 1993 and entitled Clean Room Air System; U.S. Pat. No. 5,192,348 issued Mar. 9, 1993 and entitled Directional Air Diffuser Panel for Clean Room Ventilation System; U.S. Pat. No. 5,014,608 issued May 14, 1991 and entitled Clean Room Air System; and U.S. Pat. No. 4,859,140 issued Aug. 22, 1989 and entitled Centrifugal Fan.
Cleanroom ceiling structures have been constructed in using rail elements to establish a plurality of rectangular spaces receiving the filter panels therein. Generally, a set of rail structures, e.g., extruded aluminum structures, organized in grid-fashion establish the support structure for the filter panels. In addition to filter support, cleanroom ceiling grid structures also incorporate lighting elements in downward-facing channels of the grid structure rail elements. Also, fire suppression systems have been incorporated into the grid structure and allow penetration, through the plane of the grid structure, by a fire sprinkler element coupled to water supply conduits thereabove. Ceiling grid structures have been built in modular form, sometimes constructed at an installation site and sometimes shipped from a manufacturing site to an installation site as a module. Modules join in an array to establish a ceiling grid structure.
Within grid modules, the rail elements include various structures and features including a downward-facing channel typically enclosing a light fixture and including one or more upward-facing troughs containing a gel sealant. The upward-facing troughs surround in moat-fashion each rectangular opening. Filter panels are placed over the rectangular openings. The filter panels include downward-projecting knife structures. The gel sealant enters the troughs in a low-viscosity state and flows about the trough structures. After the gel sealant flows about and occupies the trough structures, it partially solidifies and becomes more viscous. Once the gel sealant achieves a sufficient level of viscosity, i.e., becomes sufficiently solidified, the knife structures of the air filter panels enter the body of semi-solidified gel sealant and establish an air tight seal between the rail structures and the air filter panels. In this manner, air forced downward and against rail element grid and against the filter panels has no path through the ceiling module other than through the air filter panels. More particularly, because the rails themselves provide no air passage and because the gel sealant establishes an air tight coupling between the rails and the filter panels, no air passes through the module other than through the air filter panels.
Rail elements differ, however, at the perimeter of the ceiling modules. By providing a xe2x80x9chalf-railxe2x80x9d at the perimeter of each module, joining together two such half-rails from adjoining modules creates the equivalent of a complete rail structure spanning two adjoining ceiling modules. The structure thereby established is functionally equivalent to the interior rail structures of the module providing such features as a downward-facing channel and trough structures receiving gel sealant and the knife structures of the filter panels. Unfortunately, bringing together two such xe2x80x9chalf-railsxe2x80x9d at the perimeter of adjoining ceiling modules introduces the possibility of alternate air passage ways, i.e., air leaks, relative to the ceiling structure. More particularly, the interface between two such half-rails provides opportunity for air flow bypassing the filter panels and degrading air filtration. In other words, it introduces the possibility of unfiltered air flow into the controlled environment.
The generally accepted method of preventing such unfiltered air flow into the controlled environment is by caulking material applied at the interface between half-rail elements, typically at the lower boundary of such face-to-face contact. In some cases, the half-rail elements include a corner-notch structure at the lower boundary of the face-to-face contact region between half-rails. When the half-rails come together, these corner-notch structures establish a downward-facing groove structure generally located at the upper portion of the downward-facing channel formed by the combined half-rails. Caulking material is then applied along the length of the combined half-rail structure in an attempt to prevent air flow through the face-to-face contact region between the half-rails, i.e., in an attempt to establish a seal against unfiltered air flow into the controlled environment.
Unfortunately, such caulking material has failed to satisfy completely the intended sealing function. Caulking material typically cannot be applied in uniform and continuous fashion, i.e., without stopping during application. At such lap points, i.e., where the application of caulking material temporarily stops, leaks typically occur. Also, caulking material itself has a limited functional life and, over time, tends to shrink the possibility of air leaks. Finally, requiring meticulous manual placement of caulking material introduces a significant additional manufacturing step at the installation site.
It would be desirable, therefore, to better prevent air flow bypassing the filtration system and thereby increase the quality of and control over air entering the controlled environment.
A ceiling module perimeter seal establishes an air-tight seal between modules forming a ceiling structure or between a module and an adjacent wall. The seal includes structures about the perimeter of modules and aligned relative to corresponding structures of an adjoining module. Aligned structures in adjacent ceiling modules establish an enclosure between modules suitable for receiving a seal including a gasket or for coupling to apertures fluidly connecting the enclosure with gel sealant troughs of the ceiling structure whereby gel sealant flowing in the troughs enters the enclosure and thereby establishes an air tight seal between adjoining ceiling modules.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation of the invention, together with further advantages and objects thereof, may best be understood by reference to the following description taken with the accompanying drawings wherein like reference characters refer to like elements.
Under either embodiment of the present invention, first and second structures position for alignment to establish an enclosed space receiving a seal therein an providing an airtight interface between the first and second structures.